(a) Field of the Invention
The present invention relates to a supplementary wheel support chassis for a motorized wheelchair, and more particularly, to one that allows an auxiliary wheel and a tilt-proof wheel grab the ground at the same time while maintaining the central gravity of the wheelchair within the chassis to achieve a smooth driving.
(b) Description of the Prior Art
A motorized wheelchair generally available in the market is transmitted with four wheels constantly on the ground. The wheelchair is vulnerable to tilt over when bumping into a pit or climbing up or down a slope due to instable central gravity of the wheelchair. Therefore, as taught in the motorized chair base disclosed in U.S. Pat. No. 6,179,076, the manufacturing industry of motor-driven vehicle has come up with a design to have six wheels to grab the ground for achieving better stable central gravity. The six-wheel design is applicable to motor-driven cars including the power wheelchair by providing two motor-driven wheels in the existing 4-wheel structure so to keep the body stabilized with six wheels firmly grabbing the ground when traveling on rough road.
The six-wheel design is able to keep all six wheels contacting the ground in case of a rough road. However, the motor-driven wheels are provided at the center of the structure and only the motor-driven wheel is provided with a spring while the 4-wheel structure is fixed to where below four ends of the base. There is no spring or similar buffer provided between the base and those four wheels, meaning that the relative height of those four wheels is fixed. As a result, any higher protrusions, deeper pits or other barriers are found on the road, those four wheels may get stuck to prevent the car from moving on. Furthermore, the base on top of those four wheels shakes and swings in four directions to make the driver very uncomfortable since the relative height among four wheels is fixed.
The primary purpose of the present invention is to provide a supplementary support for a motorized wheelchair to keep the central gravity of the car within its chassis to achieve a smooth ride for the driver. To achieve the purpose, the present invention includes a chassis, rockers, wheel supports, buffers, springs, auxiliary wheels and tilt-proof wheels. Wherein, both side rods of the chassis are respectively pivoted to one end of the rocker. Another end of the rocker is pivoted to the wheel support and a buffer is fixed between the bottom of the chassis and the rocker. The wheel support bends for its both ends and a bending portion to define a triangle. Both ends of the wheel support are respectively pivoted to the auxiliary wheel and the tilt-proof wheel. The bending portion of the wheel support is pivoted to another end of the rocker. Both ends of the spring are respectively provided on the rocker and the wheel support. The wheel support is driven by the auxiliary wheel to rise for the tilt-proof wheel to descend to grab the ground and twist the spring. And the wheel support is restored to its original position by the spring upon the wheelchair is back on a flat road.
Another purpose of the present invention is to provide a supplementary wheel support with absorption. To achieve the purpose, a buffer is provided between the chassis and the rocker. The buffer is sandwiched by two hardwood pieces, and both hardwood pieces are packed with a resilient buffer pad. The buffer pad contains inside a hollow portion with the outer side of each hollow portion being provided with a gap for the buffer to function of absorption when the car travels on a rough road.